Furan resins modified with carboxy containing copolymer

ABSTRACT

Process for reducing the amount of shrinking that occurs when a furan resin is cured which comprises adding to a furan resin from 15 to 50 percent by weight based on the total weight of the binding material, of a copolymer of (a) at least one Alpha , Beta -olefinically unsaturated carboxylic acid component which is at most dibasic and has not more than four carbon atoms and (b) a copolymerizable olefinically unsaturated monomer having from 2 to 18 carbon atoms in a ratio of a) to b) from 1:0.5 to 1:20, said copolymer having an average molecular weight of 400 to 3000, and moulded bodies comprising a cured furan resin containing a copolymer as defined above.

United States Patent Lorentz et al.

[ Sept. 5, 1972 [54] FURAN RESINS MODIFIED WITH CARBOXY CONTAININGCOPOLYMER [73] Assignee: Chemische Werke Albert, Wiesbaden-Biebrich,Germany [22] Filed: April 21, 1971 [21] Appl. No.: 136,232

30 Foreign Application Priority Data April 25, 1970 Germany ..P 20 20260.2

[52] US. Cl. ..260/829, 260/78.5 R, 260/874, 260/897 R [51] Int. Cl...C08f 31/04 [58] Field of Search ..260/829 [56] References Cited UNITEDSTATES PATENTS 2,366,049 12/ 1944 Payne ..260/829 2,399,055 4/ 1946Nordlander ..260/ 829 2,749,322 6/ 1956 Lissant ..260/829 3,597,3868/1971 Brabander ..260/829 3 ,600,290 8/1971 Fitko .260/ 829 PrimaryExaminer-Paul Lieberman Attomey-Hammond & Littell ABSTRACT Process forreducing the amount of shrinking that occurs when a furan resin is curedwhich comprises adding to a furan resin from 15 to 50 percent by weightbased on the total weight of the binding material, of a copolymer of (a)at least one a,B-olefinically unsaturated carboxylic acid componentwhich is at most dibasic and has not more than four carbon atoms and (b)a copolymerizable olefinically unsaturated monomer having from 2 to 18carbon atoms in a ratio of a) to b) from 1:05 to 1:20, said copolymerhaving an average molecular weight of 400 to 3000, and moulded bodiescomprising a cured furan resin containing a copolymer as defined above.

10 Claims, No Drawings FURAN RESINS MODIFIED WITH CARBOXY CONTAININGCOPOLYMER This invention is concerned with improvements in or relatingto furan resins. In particular the invention is concerned with a processfor reducing the amount of shrinkage occurring in furan resins.

Furan resins may be prepared by condensing furfuryl alcohol with anacid, if desired in the presence of furfural or by condensing furfuralwith a carbonyl compound in the presence of a basic catalyst, the latterprocess being preferably carried out with a mixture of hydrocarbonshaving at least one, desirably up to three, activated double bonds. Thefirst reaction'takes place in acidic medium, for example in the presenceof catalytic amounts of dilute sulphuric acid. Such resins may beapplied together with furfuryl alcohol or a mixture of furfuryl alcoholand furfural. The second reaction involves an aldol condensation and maybe carried out, for example, in the presence of a mixture of causticsoda and sodium acetate or sodium phosphate. Suitable carbonyl compoundsare, for example, aldehydes such as acetaldehyde, propionaldehyde,butyraldehyde, isobutyraldehyde, Band acrolein and ketones such asacetone, methylethylketone, methylisobutylketone, diisobutylketone andacetophenone. Examples of hydrocarbons with activated double bonds arecyclopentadiene, dicyclopentadiene, indene, fulvene, 1,4-hexadiene andSmethylnorbomene.

The curing of furan resins prepared as described above can be effectedwith acid catalysts, for example with p-toluene sulphonic acid, amidosulphonic acid and B-naphtalene sulphonic acid. Furan resins tendhowever, to shrink substantially during curing so that their utilitywhich would otherwise be considerable because of their excellent alkaliresistance, is severely limited. This tendency to shrink is particularlymarked whenever the furan resins are used as binders in jointing andtiling compositions, for example, for acid-proof bricks and carbonbricks normally employed in acidproof constructions.

According to the invention there is provided a process for reducing theamount of shrinking that occurs when a furan resin is cured whichcomprises adding to a furan resin from to 50 percent by weight based onthe total weight of the binding material of a copolymer of (a) at leastone a,B-olefinically unsaturated monoor dibasic carboxylic acidcomponent having not more than four carbon atoms and (b) acopolymerizable olefinically unsaturated monomer having from 2 to 18carbon atoms in a ratio of a) b) from 110.5 to 1:20, said copolymerhaving an average molecular weight of 400 to 3000. Very often thecontent of component b) is from 50 to 95 mol percent.

Preferably the copolymers also contain a telogen component.

The term acid component as used herein means the free acids and theiranhydrides and half esters, where such exist. The copolymers obtainedmay thus contain free carboxyl groups and/or anhydride groups.

The copolymers preferably have an average molecular weight of from 500to 2,000 and desirably from 600 to 1,500. The copolymers generallycontain from 0.08 to 0.9 percent carboxyl groups of correspondinganhydride groups per 100 molecular weight units. The preferredcopolymers are those containing a high proportion of carboxyl groups oranhydride groups. The copolymers may be prepared by polymerization ortelomerisation of components (a) and (b) above. Suitable olefinicallyunsaturated, monoor dibasic carboxylic acid components include acrylicacid, methacrylic acid, maleic acid, maleic anhydride and half-esters ofmaleic acid with monohydric alcohols e.g., those alcohols having from 1to 12 carbon atoms. Preferred olefinically unsaturated monomers are themonoolefinically unsaturated compounds such as monoolefins, with from 2to 9 carbon atoms, particularly the a-olefins. Suitable olefinicallyunsaturated compounds thus include ethylene; propylene; butylene;octene; styrene or styrene derivatives such as the various vinyltoluenes; a-methyl styrene; vinyl monomers; derivatives of acrylic ormethacrylic acid e.g., esters, amides or nitriles thereof; vinylpyridine; vinyl pyrrolidone and allyl compounds such as allyl ester orethers. The derivatives of acrylic or methacrylic acid are preferablypolymerized together with maleic anhydride. If these derivatives areesters, they may be derived from monoor dihydric alcohols. Illustrativeof such derivatives are methyl-, ethyland butyl-acrylate andmethacrylate, and ethylene glycol, propylene glycol or 1,3-butanedioldimethacrylate or diacrylate. Particularly suitable copolymers are thosecontaining from 60 to mol percent of a vinyl aromatic compound of theformula CH=CH wherein X and Y which may be the same or different mayeach be hydrogen, chlorine, bromine or methyl provided that not morethan one halogen atom and one methyl group is present in the nucleus.

The olefin-carboxylic acid copolymer is preferably a styrene-maleicanhydride telomer and preferably has a molar ratio of carboxylic acidcomponent olefin of from 1:0.5 to 1:20, preferably from 1:1 to 1:8. thefollowing telomers are suitable starting materials: (a) styrene-maleicanhydride telomers in the molar ratio 1:1, 2:1, 3:1, 5:1 or 8:1, (b)octene-maleic anhydride telomers in the molar ratio of 1:1, (c)styrene-acrylic acid teloemrs in the molar ratio of 1:1 and (d)styrenevinyl toluene-maleic anhydride telomers in the molar ratio offrom 1:1:1 to 311:2, e.g. 1:1:1, 1:1:2 or 3:122. The preferred telomersare (a) and (b).

The copolymer may also contain cumene or cymene as a telogen or, ifdesired, other telogens such as pxylene, or the other xylenes or isomermixtures of lenes toluene, benzene, chloroform, methyl ethyl ketone ordiisobutyl ketone or a combination thereof.

The proportion of telogen component may be up to 35 percent by weight ofthe copolymer and is preferably from 5 to 25 percent, in particular upto 20 percent by weight of the copolymer. The optimum content of telogenwill depend on the molecular weight which it is desired that thecopolymer shall have and on the chemical character of the telogen. Forexample copolymers with an average molecular weight of from about 600 to700 may have a telogen content of from about 15 to 18 percent by weightand those with an average molecular weight of from about 1,000 to 1,500may have a telogen content of up to 5 percent by weight. Generally thetelogen content should be higher in a copolymer havinga lower molecularweight and vice versa.

The copolymers may be prepared by any of the usual methods, for example,copolymerization may be carried out in a solvent, e.g. at a temperaturein excess of 150 C. for example from 170 to 220 C. The reactioncomponents are thus added to the solvent, if desired,

together with a peroxide initiator. The copolymer formed may be obtainedeither by precipitation or by distilling off the solvent. The telogenslisted above can be used as solvents. I

According to one modification of the invention furan resins hardenableby acids can be produced from furfuryl alcohol, if desired in admixturewith furfural, even under the conditions to form shaped articles and canimmediately be hardened. Thisoffers the advantage that it is notnecessary to separately produce the furan resin in advance. Such resinsshow only, low shrinkage as well as'excellent stability. The acidresistance is however, not as good as that of a precondensed furanresin. In every case, however, the incorporation of the copolymer isfacilitated by the presence of furfuryl alcohol and possibly furfuralbecause it is soluble in these materials.

It is also possible to process the copolymers with a combination of (1)furan resin and (2) furfuryl alcohol or mixtures of furfuryl alcohol andfurfural. The weight ratio of component (1) to component (2) may be from10:1 to 05:1, preferably from 4:1 to 1:1. If furfural is used the amountemployed should not be more than 50, preferably not more than 35percent, by weight of the furan resin and in general not more than 50percent, preferably not more than 35 percent, by weight of the furfurylalcohol. 4

Several methods of assessing shrink characteristics are available. Amethod that has proved highly satisfactory in practice is to lay ceramictiles in a 1 cm bed of cement with 1 cm wide butt joints. Forpreliminary experiments square tiles with an edge length of 7 cm, athickness of 15 mm and an overall length of 31 cm may be used. These arereferred to below as small size specimens.

For more precise measurements, 8 so-called ceramic gap tiles having athickness of 25 mm, and an edge length of 1 10 mm are laid in a 10 mmbed of cement, providing for 10 mm butt joints. These specimens arereferred to below as large size specimens. The cement is applied to afoil to which it does not adhere so that the displaceability of thecement bed is not impaired. Shrinkage will result in warping of thisbeam which is about 1 meter long. The maximum warping of the tile beamin mm is taken as the degree of shrinkage. The tile beam is stored forfive days at room temperature, then for 16 hours at 50 C. andsubsequently for some days at 60 C. Measurement is always carried outwhile the beam is warm.

In order thatthe invention may be well understood the following examplesare given by way of illustration only.

Examples 1-4 The composition of the mixtures and the results obtainedwill be found in table 1 in the appendix. The furan resin solutionmentioned in this table is a resin obtained by auto-condensation ofparts by weight furfuryl alcohol in the presence of 1.4 parts by weight5 percent sulphuric acid and that was dissolved in 30 parts by weightfurfural. The filler is a mixture of coke flour with a grain size offrom 0.01 mm to 0.38 mm. Curing is effected with the acid ofamidosulphonic acid.

. The products obtained in Examples 1 to 3 were tested to determinewhether, after curing, a physical mixture of a) the telomer with bl)furfuryl alcohol and furufral or b2) with furfuryl alcohol, furfural andthe furan resin was present or whether a chemical reaction had occurred.For this test, cement cylindersw ere boiled in acetone and chloroform.After 40 hours of boiling, the 'cylinders in accordance with example 1suffered a loss equivalent to the amount of telomer added. In the caseof the cylinders in accordance with example 3, there was a loss of lessthan 1 percent which leads one to the conclusion that the telomer hasbeen built in. If one merely wishes to reduce the degree of shrinkagewhile utilizing the excellent chemical stability of thefurfural-furfuryl alcohol condensate, such compositions can be usedsince other physical characteristics are not affected. If however, onewishes to have increased resistance to chemical attack thecopolymerization products should be combined with a pre-condensed furanresin and preferably also with furfural and furfuryl alcohol.

The dilatometric behavior (the expansion behavior under heat) of thecompounds of comparative example A and examples 2 to 4 was assessed. Thesamples investigated had the approximate dimensions 5 X 5 X 40 mm. Thevalues were measures after 7 days of air storage (m) and a further 16hours of storage at C. (n).

The samples were heated at a rate of 2.6 C. per minute to a temperatureof C. (sample m) and at a heating rate of 1.2 C. per minute to atemperature of C. in the case of sample (n). With sample (n) the lesserheating rate is necessary because, as a result of the ageing that hasalready taken place, dilatometric changes occurmore slowly. To establishthe behavior of sample (n) under thermal load, the temperature was keptconstant for 5 hours after reaching a value of 150 C. Subsequently, thespecimen was cooled to room temperature over a period of 20 minutes bywithdrawing it from the oven. The results are shown in table 2. l

The mixture described in Example 2, which showed the best chemicalresistance at low shrinkage, offers the following further advantages incomparison with formulation A: a

a. the adhesion to ceramics is better. After 10 days air storage, avalue of 2.1 kg/cm was recorded for A and 21.4 kg/cm for the product ofExample 3.

b. the irreversible thermal elongation (itE) is improved. The valuesare: after 72 hours at 120 C. for A 0.34 percent and for Example 3 0.23percent itE after 72 hours at 230 C. for A 0.19 percent and for Example3 0.42 percent itE (negative itE values indicate shrinkage).

An irreversible thermal elongation under the action of heat is ofadvantage since when the furan resin is used as a cement for the liningof containers it will greatly promote the density of the lining.

Example 5 100 parts by weight furan resin telomer (as described inExample 3) and 500 parts by weight of a filler consisting of 60 parts byweight quartz flour H31, 30 parts by weight quartz flour W (bothcommercial products of Quarzwerke Frechen near Cologne, Germany, 2 partsby weight amidosulphonic acid and 0.5 part by weight p-toluene sulphonicacid, were mixed and a large size specimen as described for Example 3was prepared from this. As comparison, a mixture of 100 parts by weightsolution according to A were made into a cement with 500 parts by weightof the above quartz flour/acid mixture and an identical shrink beamprepared. Both shrink beams were stored as described in both air andheat and the warping measured. The results are shown in table 3. In thiscase the already low shrinkage is reduced by half as a result of theadditive in accordance with the invention.

Example 6 The addition of the telomer also influences the shrinkage ofthose furan resin/filler mixtures in which the furan resin is used as acondensation product from furfural and a low aliphatic aldehyde orketone.

In accordance with Example 1 of German Pat. No. 1,048,413 a liquidcondensate with a viscosity of approximately 200 e? at 20 C. is preparedfrom 1 mol furfural, 1 mol acetaldehyde and 0.25 mol dicyclopentadiene.A solution is then prepared from 75 parts by weight of this condensateand 25 parts by weight of the telomer used in Example 1. This solutionhas a viscosity of approximately 800 cP at 25 C. 100 parts by weight ofthis solution are mixed with 185 parts by weight of a mixture from 95parts by weight coke flour of granulation 0.01 to 0.48 mm, 4.25 parts byweight p-toluene sulphonic acid and 0.75 part by weight dimethylaniline,a shrink beam (large size specimen) then being prepared. For comparison,a shrink beam is also prepared which contains in the cement a resinsolution in accordance with example 1 of German Pat. No. 1,048,413 asbinder. The resin solution and the tiller described above are mixed inthe ratio stated below. The results are shown in table 4.

same consistency. Shrinkage, in each case in mm warping:

Small size specimens After 5 days air storage 0.2 0 0 after 1 day at 60C1.0 1.6 1.3 0.6 0 0.2 0 0 after 2 days at 60C 1.2 1.8 1.7 1.0 0 0.2 00.1 after 3 days at 60C 1.6 1.9 1.7 1.0 0 0.2 0.1 0.1 after 6 days at60C 1.9 2.7 1.9 1.2 0 0.3 0.1 0.2 after 7 days at 60C 2.1 2.8 2.3 1.60.1 0.4 0.2 02

Large size specimens after 5 days air storage 0.1 0 after a further 1 16hours at 50C 4.6 0.3 after a further 24 hours at 60C 13.3 0.7

Comparison Example A B C D l 2 3 4 after a further 24 hours at 60C 14.71.3

Table 2 Expansion behavior under heat Comparison Example (m) 7 days airstorage 0.49% 0.16% 0.07%

0.19% (n) after further 0.12% 0.04% 0.04% 16 hours at C 0.01% total0.61% 0.20% 0.11%

Table 3 (referring to Example 5) Time Temp. Shrinkage: Warping in mm Cwith solution Comparison A according to example 3 5 days 20-22 0.01 0.2further 16 hours 50 0.25 0.45 further 24 hours 60 0.65 1.35 further 24hours 60 1.05 2.10 further 24 hours 60 1.65 2.95

Table 4 (referring to Example 6) Comparison of shrinkage Warping in mmTemp. with addition without addition 5 days 20-23 0.2 0.1 further 16hours 50 0.2 2.6 further 24 hours 60 0.7 9.4 further 24 hours 60 1.0 I14.3 further 24 hours 60 1.0 failed as stress too high What we claim is:

1. A process for reducing the amount of shrinking that occurs when afuran resin is cured which comprises adding to a furan resin from 15 to50 percent by weight based on the total weight of the binding material,of a copolymer of (a) at least one a,B-olefinically unsaturatedcarboxylic acid component which is at most dibasic and has not more thanfour carbon atoms and (b) a copolymerizable olefinically unsaturatedmonomer having from 2 to 18 carbon atoms in a ratio of a) to b) from1:0.5 to 1:20, said copolymer having an average molecular weight of 400to 3,000.

2. A process as claimed in claim 1 in which the copolymer'is processedwith a combination of 1 furan resin and (2) furfuryl alcohol or amixture of furfuryl alcohol and furfural respectively wherein the ratioof the weight of component (1) to component (2) is from 10:1 to 0.521.

3. A process as claimed in claim 1 in which under conditions to formshaped articles acid hardenable furan resins are prepared from a)furfuryl alcohol or b) furfuryl alcohol and furfural and hardened.-

4. A process as claimed in claim 1 in which the copolymer contains atelogen component derived from copolymer contains from to 25 percent byweight of telogen.

9. A process as claimed in claim 1 in which the furan resin is processedwith furfural and the amount of furfural used is not more-than 50percent by weight based on the furan resin and not more than 50 percentby weight based on the furfuryl alcohol.

10; Mouldedbodies comprising a cured furan resin containing a copolymerin accordance with the process as claimed in claim 1.

2. A process as claimed in claim 1 in which the copolymer is processedwith a combination of (1) furan resin and (2) furfuryl alcohol or amixture of furfuryl alcohol and furfural respectively wherein the ratioof the weight of component (1) to component (2) is from 10:1 to 0.5:1.3. A process as claimed in claim 1 in which under conditions to formshaped articles acid hardenable furan resins are prepared from a)furfuryl alcohol or b) furfuryl alcohol and furfural and hardened.
 4. Aprocess as claimed in claim 1 in which the copolymer contains a telogencomponent derived from cumene, cymene, xylene or a combination thereof.5. A process as claimed in claim 1 in which the copolymers have anaverage molecular weight of 500 to 2,000.
 6. A process as claimed inclaim 1 in which the total of carboxylic groups in the copolymerincluding those which are present in the form of anhydrides is between0.08 and 0.9 percent per 100 molecular weight units.
 7. A process asclaimed in claim 1 in which the olefinically unsaturated monomer is amono-olefin with from two to nine carbon atoms.
 8. A process as claimedin claim 1 in which the copolymer contains from 5 to 25 percent byweight of telogen.
 9. A process as claimed in claim 1 in which the furanresin is processed with furfural and the amount of furfural used is notmore than 50 percent by weight based on the furan resin and not morethan 50 percent by weight based on the furfuryl alcohol.
 10. Mouldedbodies comprising a cured furan resin containing a copolymer inaccordance with the process as claimed in claim 1.